About the US/LHC Project

The Large Hadron Collider at CERN near Geneva, Switzerland is opening new vistas on the deepest secrets of the universe, stretching the imagination with newly discovered forms of matter, forces of nature, and dimensions of space. This site provides general information about the Large Hadron Collider and detailed information about American participation in the LHC accelerator and experiments. U.S. LHC participation is supported by the US Department of Energy's Office of Science and the National Science Foundation.

A proton-proton collision event in the CMS experiment producing two high-energy photons (red towers). This is what we would expect to see from the decay of a Higgs boson but it is also consistent with background Standard Model physics processes. (Courtesy: CERN)

What is the Large Hadron Collider?

The LHC at CERN, the European Organization for Nuclear Research, is the largest, most complex and most powerful particle accelerator ever built. It operates in a circular 27-kilometer tunnel about 100 meters underground, between Switzerland's Lake Geneva and France's Jura mountains. The LHC creates almost a billion proton-proton collisions per second at an energy of 8 trillion electron volts, the highest any accelerator has achieved.

At the heart of the LHC are superconducting magnets made of niobium-titanium. Cooled to nearly absolute zero by superfluid helium, the coils of these magnets conduct electricity without resistance. The LHC's 1,232 dipole magnets guide the opposing beams of speeding protons in their circular orbits. Several thousand additional magnets fine-tune the beams' orbits, and some 400 quadrupole magnets focus the protons into hair-thin beams that collide within the LHC experiments. Cryogenic, electronic and information systems of unprecedented scope and complexity support the LHC's 'round-the-clock operation.

The LHC physics program mainly uses proton-proton collisions, but the LHC can also accelerate lead ions to create collisions with an energy of 1,150 TeV during shorter running periods, typically one month per year.